I've never had Gerbil agression before in my house, but there is a first time for everything. As near as I can put it all together, Big Mamma, tired of Big Daddy spending time with Little Momma, destroyed a newly pregnant LM. Big Mamma is more heavily pregnant and I guess she was securing resources for her litter.
I'm going to do some more research before moving forward with my planned Gerbil colony, compost offerings sometimes snake food project. I thought gerbils would be a lower volume compost source than rabbits, but I didn't take into account the agression factor and frankly, I've never seen it before.
I have heard of it running in rodent families though, so Big Mamma and her offspring will probably be moved to the perimeter of the colony and watched. The fiercest Momma animals are often the best Moms, so I will just watch what happens.